The E3SM Atmosphere Model and E3SM Land Model have a complex system for configuring its compile- and runtime-options that was inherited from CESM
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/qfs/people/jaco316/E3SM/components/cam/bld/configure -s -ccsm_seq -ice none -ocn docn -caseroot /qfs/people/jaco316/E3SM/cime/scripts/FLbase -comp_intf mct -spmd -spmd -smp -nosmp -dyn se -dyn_target preqx -res ne30np4 -phys cam5 -clubb_sgs -microphys mg2 -chem linoz_mam4_resus_mom -rain_evap_to_coarse_aero -nlev 72 -bc_dep_to_snow_updates
“-phys cam5” is first because it is also earlier in the CAM_CONFIG_OPTS block.
“configure” is called by the eam/cime_config/buildnml script.
Multiple matches will ADD up to the final configure line because of this line in the CAM_CONFIG_OPTS block
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/qfs/people/jaco316/E3SM/components/cam/bld/build-namelist -infile /qfs/people/jaco316/E3SM/cime/scripts/FLbase/Buildconf/camconf/cesm_namelist -csmdata /compyfs/inputdata -ignore_ic_year -use_case 2000_cam5_av1c -inputdata /qfs/people/jaco316/E3SM/cime/scripts/FLbase/Buildconf/cam.input_data_list -ntasks 900 -namelist " &atmexp /
And this call creates the atm_in file read in by the model at runtime.
“build-namelist” is also called by buildnml in eam/cime_config AFTER the call to “configure”.
The use case file is recorded in the casedir in env_run.xml
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